Cellulose plisse fabric and method of producing by applying 1, 3-bis(hydroxy-methyl)-2-imidazolidone and chemical shrinking agent



having fine yarns.

United States Patent CELLULOSE PLISSE FABRIC AND METHOD OF PRODUCING BY APPLYING 1,3-BIS(HYDROXY- METHYL)-2-'IMIDAZOIJ1DONE AND CHEMICAL SHRINKING AGENT Winnifred A. Wardell, Charlotte, N. C., assignor to Rohm & Haas Company, Philadelphia, Pa .a corporation .of Delaware No Drawing. Application April 8, 1954, Serial No. 421,963

20 Claims. (Cl. -8-114.5)

This invention relates to puckered or pliss fabrics comprising cellulosic fibers, filaments, and yarns and to methods of producing them.

Heretofore the normal pliss process involved the application to local areas of ,a shrinking agent, such as .caustic soda, to fabrics of low count construction and When crinkled or puckered effects were desired in high count fabrics or coarse yarn fabrics, it was generally necessary to resort to creping operations which utilized high twist yarns, such as from 35 to 90 turns per inch in order to produce the shrinkage efiects desired.

It is an object of the present invention to provide improved pliss fabrics comprising cellulose fiber-containing yarns of normal twist which .are stable against dimensional shrinkage and loss of pucker or pliss even when washed or laundered, and methods of producing them. A further .object is to provide improved pliss fabrics in :which the fibers, filaments, and yarns formed thereof are substantially unchanged in luster, sheen, and opacity and other optical appearances and methods of producing them. A further object is ,to provide improved pliss fabrics having improved hand or feel and ;to methods of producing them. A further object of the invention is to provide improved pliss fabrics, and methods .of producing them, which have a high yarn count, such as over 60 picks per inch, as in ehambrays or ginghams. A further object of the invention is to provide improved pliss fabrics and methods of producing them which comprise coarse yarns, such as denims and ducks. A further object is to provide improved methods for making pliss fabrics which are highly versatile and capable of producing pliss or pucker in a wide variety of textile fabrics, in which the pliss may extend in either the warp, filling, or any other direction, that are substantially permanently stable against dimensional change and loss in pucker during normal laundering operations. Other objects and advantages of the invention will be apparent from the description thereof hereinafter.

In accordance with the present invention, the fabric containing yarns of normal twist comprising cellulosic fibers or filaments is treated over all its area with a linear cross-linking agent consisting essentially of 1,3-bis-(hydroxymethyl)Z-imidazolidone of the formula The fabric is then dried in tensioned or stretched condition and the cellulose of the fibers or filaments is reacted with the imidazolidone by heating, for example, by continuing the drying for a sufficient period of time at a sufficiently high temperature, or by heating in a separate step after drying. Thereafter a shrinking agent, such as caustic soda, is applied locally. Upon washing and subsequent drying, the pliss fabric is obtained.

An essential element of the process is the application Patented Oct. .22, 1957 of the particularzimidazolidone defined hereinabove which is a cross-linking agent that is incapable of producing an insoluble, three-dimensional resinous condensate by condensing with itself. The imidazolidone, therefore, cannot produce an insoluble fiber-ensheathing covering or an interstitial filling resin, such as would be produced from cross-linking agents of the type that forms insoluble, three-dimensional resins by self-condensation or polymerization, such as the urea-formaldehyde, melamineformaldehyde and phenol-formaldehyde types. Because of the self-condensation or polymerization of the latter types of materials to-insoluble resinous condensates, crosslinking cellulose with such materials would require application to the fabric of a much greater proportion of cross-linking agent to produce stabilization against Washing; such materials would, therefore, modify the fabric in its optical and tactical characteristics, for example, by changing its lusteror transparency by harshening its hand and so forth. They also tend to produce unevenly distributed resinous deposits which give rise to irregularity in dyeing.

The imidazolidone in the amounts required to stabilize the fabric produces substantially no change in hand or in optical characteristics of the fabric. Fabrics to which the imidazolidone has been applied show good uniformity in dyeing with all such dyes as are suitable for the particular material of which the fabric is composed, such as With direct, naphthol, dispersed acetate, or acid dyes. The imidazolidone also prevents the transparentizing action of caustic soda or other shrinking agent solutions, especially on cotton.

In accordance with the present invention, the fabrics that may be treated are those which contain a substantial .and preferably a predominant proportion of cellulosic fibers and/or filaments. It is particularly useful with woven fabrics of cotton, viscose rayon, cuprammonium cellulose rayon, linen, as well as to fabrics comprising yarns of filaments and fibers of two .or more .of the abovementioned cellulosic materials. The fabric may contain filaments, fibers or yarns .of materials other than cellulose provided sufiicient cellulosic yarns be present to exert-the shrinkage effect upon application of the shrinking agent that is necessary to produce the pliss effect. The fabric may be in the greige state or it may have been previously bleached, dyed and/ or printed with pigments or otherwise finished.

The imidazolidone is water-soluble and it may advantageously be applied to the fabric by way of an aqueous medium. For this purpose, a solution in water of 1-15 concentration may be prepared and applied to the fabric, as in a textile padder, a roll coater, or by brushing, spraying, or in a jig. Concentration and conditions of application may be controlled to provide from /2 to 7 /2% or more pick-up of the imidazolidone on the Weight of the fabric. Preferably from 1 to 4% is applied to the fabric.

An acidic catalyst is provided in the imidazolidone solution for the purpose of accelerating the reaction thereof with the cellulose which is believed to take place on the hydroxyl groups thereof. The catalysts used may be ammonium phosphate, ammonium thiocyanate, hydrochloric or other acid salts of a hydroxy aliphatic amine including 2 methyl 2 amino 1 propanol, 2 methyl- 2 amino 1,3 propandiol, tris(hydrox-y- -methyl)arninornethane, 2 phenyl 2 amino 1 propanol, 2 methyl 2 amino 1 pentanol, 2 aminobutanol, triethanolamine, 2 amino 2 ethyl l butanol, also ammonium chloride, pyridine hydrochloride, benzyldimethylamine oxalate. The amine salts are water-soluble latent catalysts substantially neutral at ordinary temperature but dissociate into volatile componentsone .of which is acidic at the elevated temperatures ing the fabric in succession through aqueous baths containing the imidazolidone or the catalyst respectively, the

fabric is dried while in tensioned or stretched condition.

Depending upon the effect desired, the fabric may be tensioned widthwise (that is, fillingwise) or warpwise or in both directions at once. For specialty effects, the direction of tension may even be at an angle to the warp or filling directions of the fabric. The degree of tension may vary from that which is merely necessary to remove all slack to as much as that required to extend one or both directions of the fabric as much as 10-15%. The greater the tension applied at this stage, the greater the puckering or pliss effect that is finally obtained. The drying stage may serve to initiate reaction between the hydroxyl groups of the cellulose and the imidazolidone, and it may be prolonged for a period of time adequate to complete such reaction. The fabric may be dried at a temperature of 200 F. or higher and it may be retained in the tensioned condition at the drying temperature for a sufficient period of time to complete the reaction of the imidazolidone with the cellulose of the fabric. Preferably, temperatures of 250 F. to 400 F. or higher are used for completing the reaction with the cellulose. A period of about 20 minutes is satisfactory at the lower temperature of 250 F. just mentioned, whereas the time required gradually decreases with increased temperature until a period of about 10-30 seconds is needed at the upper limit of the range just mentioned.

The baking or curing operation which causes the imidazolidone to react with and cross-link with the cellulose serves to stabilize the fabric against dimensional change on washing.

After the stabilization of the fabric with the imidazolidone, a shrinking agent is applied locally. The shrinking agent may be sodium hydroxide, potassium hydroxide, or the strong quaternary ammonium bases, such as the low molecular weight quaternary ammonium hydroxides including benzyltrimethylammonium hydroxide, dibenzyldimethylammonium hydroxide, and trimethylhydroxyethylammonium hydroxide. From the standpoint of cost, the sodium hydroxide or caustic soda is most advantageous and will be referred to hereinafter. However, the caustic potash and quaternary ammonium bases may be used instead of caustic soda wherever the latter is mentioned hereinafter. Thus, a paste of aqueous caustic soda or the like may be applied by printing or stencilling, or a caustic soda solution may be applied to the entire fabric after treatment of local areas with a resist. An aqueous 2550% concentration of caustic soda may be thickened with a suitable agent, such as starch, polyvinyl alcohol, partially hydrolyzed polyvinyl acetate, water-soluble cellulose ethers, such as methyl cellulose, hydroxymethyl cellulose, starch, ethylene oxide-modified starch, gum tragacanth, locust bean gum, and the like. The shrinking agent may be applied at normal room temperatures, at somewhat elevated temperature, or it may be refrigerated to a temperature between -5 C. and room temperature.

The caustic soda or the like may be printed in the form of any design, such as in lines which may be parallel to the length or parallel to the width of the fabric, crossed lines comprising one set parallel to the width and the other parallel to the length, or crossed lines extending at an angle to these directions, preferably at 45 thereto. The printing of the shrinkage agent may be effected in larger areas of either regular or irregular I shape to provide special designs. The design in'which the shrinking agent is printed may be correlated with the direction or directions in which the fabric is tensioned during stabilization by means of the imidazolidone. For example, the fabric may be tensioned in the filling direction and the shrinking agent may be printed in lines which extend parallel to the filling, thereby giving a maximum pliss' effect extending fillingwise of the fabric When the shrinking agent is printed in larger regular or irregular areas, such as triangles,

squares, circles, etc., the fabric may have been tensioned both warpwise and fillingwise before stabilization.

After treatment with the shrinking agent, the fabric is relaxed, washed and, if necessary, neutralized, and then dried in relaxed condition. Generally, the shrinkage develops as soon as the fabric is allowed to relax while or after the caustic soda or the like is applied and may continue through the drying stage so that upon completion of the drying in relaxed condition, the pliss fabric is obtained. This procedure may be modified to vary or control the extent and character of shrinkage by drying the fabric under tension immediately after printing with the caustic, then relaxing while Washing and neutralizing, and drying under relaxed conditions. In either of these procedures, the final drying may be effected with some tension which is sufficient to prevent the maximum development of pucker but insuflicient to completely eliminate the pucker. In these ways, the degree of pucker may be effectively varied. I

The process hereinabove described may be modified by applying a resist locally to the fabric that has been treated with the imidazolidone, either before or after the curing of the imidazolidone. For example, resinous materials which resist the action of caustic and prevent the caustic from acting upon the cellulosic fibers in the fabric may be so applied, and subsequently the whole fabric may be run through an aqueous caustic dispersion having a concentration of l535%. After application of the caustic, such as in a textile pad, by brushing, spraying, roller coating, or otherwise, the fabric is washed and preferably neutralized and then dried. Protective resists that may be used for this purpose include organic solvent soluble resinous materials, such as thermoplastic polymers and copolymers of vinyl chloride, vinylidene chloride, trifluoromonochloroethylene, ethylene, copolymers of vinyl chloride or vinylidene chloride with vinyl acetate, acrylonitrile and so on. After the caustic printing, washing, and neutralizing has been completed, the protective resist is removed by suitable organic solvents, or if thermoplastic, their removal may be assisted by heating.

On some constructions of fabrics, especially those having a high count, that is, a tight weave, and those comprising rayon yarns, it is desirable to apply a water-repellent material to the fabric prior to application of the caustic printing paste for the purpose of assuring sharp outlines and preventing wicking or migration of the caustic paste away from the edges of the printed areas. This water-repellent material may be applied to the fabric after the imidazolidone has been applied or simultaneously therewith. Particularly advantageous waterrepellent materials are those quaternary ammonium compounds having a long-chain hydrocarbon group, such as stearyl pyridinium chloride, octadecyl oxymethylpyridinium chloride, and the various quaternary ammonium salts described in U. S. Patent 2,351,581. These quaternary ammonium salts are water-soluble in the salt form and they can, therefore, readily be included within the aqueous solution of the imidazolidone. In addition, the quaternary ammonium salt may be supplemented with waterinsoluble copolymers of 0.5 to 8% by weight of acrylic acid, methacrylic acid, and itaconic acid. Any one or more of these monoethylenically unsaturated acids may be copolymerized with one or more other copolymerizable compounds containing a single vinylidene group, such as esters of acrylic acid or methacrylic acid and monohydric alcohols such as methyl, ethyl, butyl, octyl, dodecyl, cyclohexyl, cyanoethyl, aminoethyl, and the like;,esters of itaconic acid and the above alcohols; esters from maleic,

fumaric or citraconic acids, and the above alcohols; vinyl esters of carboxylic acids such as acetic, propionic, butyric, and the like; vinyloxyalkyl esters such as vinyloxyethyl acetate, etc.; vinyl ethers such as ethyl vinyl ether, butyl vinyl ether, octyl vinyl ether, hydroxyethyl vinyl ether, aminoethyl vinyl ether, aminopropyl vinyl ether, dimethylaminoethyl vinyl ether, vinyloxyethoxyethanol, vinyloxypropoxyethanol; methacrylonitrile or acrylonitrile; acrylamide, or methacrylamide, and N-substituted amides of these types; vinyl chloride, vinyl bromide, vinylidene chloride, vinylidene fluoride, vinylidene cyanide, l-chlorodfluoroethylene, ethylene, styrene, 2-vinylpyridine, 4-viny1 pyridine, 2-rnethyl-5-vinylpyridine. These water-insoluble copolymers may be dispersed by means of non-ionic dispersing agents, such as alkylphenoxypolyethoxyethanols having alkyl groups of about seven to eighteen carbon atoms and 6 to 60 or more oxyethylene units, such as heptylphenoxypolyethoxyethanols, octylphenoxypolyethoxyethanols, methyloctylphenoxypolyethoxyethanols, nonylphenoxypolyethoxyethanols, dodecylphenoxypolyethoxyethanols, and the like, polyethoxyethanol derivatives of methylene linked alkyl phenols; sulfur-containing agents such as those made by condensing 6 to 60 or more moles of ethylene oxide with nonyl, dodecyl, tetradecyl, t-dodecyl, and the like mercaptans or with alkylthiophenols having alkyl groups of six to fifteen carbon atoms; ethylene oxide derivatives of long-chained carboxylic acids, such as lauric, myristic, palmitic, oleic, and the like or mixtures of acids such as found in tall oil containing 6 to 60 oxyethylene units per molecule; analogous ethylene oxide condensates of long-chained alcohols, such as octyl, decyl, lauryl, or cetyl alcohols, ethylene oxide derivatives of etherified or esterified polyhydroxy compounds having a hydrophobic hydrocarbon chain, such as sorbitan monostearate containing '6 to 60 oxyethylene units, etc.; block copolymers of ethylene oxide and propylene oxide comprising a hydrophobic propylene oxide section combined with one or more hydrophilic ethylene oxide sections.

When the water-repellent agent or agents is or are included in the imidazolidone solution, the concentration thereof may be from 1-5 on the total weight of the solution.

Various materials may be included in the imidazolidone solution in a concentration from 1% to 7.5% by weight for modifying the hand of the finished fabric. Forexample, such materials as starch, ethylene oxide-modified starch, polyvinyl alcohol, alkali-soluble, water-insoluble cellulose ethers, such as hydroxyethyl celluose, carboxymethyl cellulose and the like may be used. The waterrepellent agents mentioned hereinabove also serve this purpose, the quaternary ammonium compounds generally exerting a strong softening effect and the water-insoluble acid copolymers tending to give a wide variety of hands from soft to firm. By suitably selecting one or more of these materials, a desired extent of water-repellency may be obtained in combination with any desired softness or firmness in the final fabric.

The fabric treated in accordance with the present invention may be a dyed fabric as stated heretofore, but if not, pigments and/or dyes may be included in the imidazolidone solution, or they may be applied by printing the fabric after treatement with the imidazolidone and drying thereof, either before or after the curing step, but before application of the caustic shrinking agent. Again, the fabric may be dyed after the completion of the pliss operation. Generally this produces a two-toned dyeing effect; the areas Where caustic printing has effected shrinkage, producing a darker or a lighter tone than the other areas depending upon the particular type of dye applied.

In another alternative procedure, yarns may be treated with the stabilization solution containing the imidazolidone before they are converted into woven fabrics. Such stabilized yarns may then be combined with cellulosic yarns which have not been stabilized, as by alternating the two types of yarns in either the warp or the weft or 6 both. For example, three stabilized yarns may alternate with three unstabilized yarns in the warp. The fabric may then be printed with caustic in areas which overlap or intersect the stabilized yarns so that on subsequent Washing, neutralization and drying, the fabric will comprise three different types of areas, some Where no shrinkage has occurred (that is those corresponding to the portions of the stabilized yarns which have not been printed with caustic), shrunken areas corresponding to the untreated yar'ns which were not printed with caustic and which shrunk upon Washing, and areas which have shrunk the maximum as a result of having been printed with caustic, whether or not they were originally stabilized by the treatment with the imidazolidone. The procedure may be modified by applying a mixture of the imidazolidone with a resist such as any of the protective resists mentioned hereinbefore, to provide stabilized yarns carrying a resist protecting them against the action of the caustic soda. After setting the imidazolidone in these yarns and weaving them with other non-stabilized shrinkable yarns into a fabric, the fabric can be padded through a solution of caustic to effect shrinkage of the untreated yarns and puckering of the others. After neutralization, the resist may be removed leaving a pliss fabric stabilized against shrinkage on washing.

The following examples illustrate the invention.

Example 1 A cotton gingham having a 60 x 60 count of thirties yarn which had been de-sized, bleached and dyed was impregnated with an aqueous solution of 1.5% of 1,3-bis- (hydroxymethyl)2-imidazolidone and 0.3% of the hydrochloride of 2-methyl-2-amino-l-propanol as a catalyst, having 1% of a copolymer of 66% ethyl acrylate, 32.7% methyl methacrylate, and 1.3% of methacrylic acid dispersed therein by 0.1% of para-tertiary-octylphenoxypolyethoxyethanol containing about eleven ethoxy groups per molecule. After impregnation the fabric is squeezed at full open width thru pad rolls. It was then dried under tension across the width on a tenter frame and cured for 1.5 minutes at 320 F. An aqueous paste of 35% caustic soda thickened with polyvinyl alcohol was then applied in parallel lines extending widthwise of the fabric. The fabric was then passed through an aqueous wash and was neutralized with sodium bicarbonate and again washed. It was then dried in a relaxed condition. The fabric showed a pronounced pliss resulting from a strong shrinkage of the fabric where caustic had been applied. The pliss effect was substantially undiminished after fifteen launderings.

Example 2 The same procedure was employed as in Example 1 except that the concentration of the imidazolidone was 4% and the concentration of the water-insoluble copolymer was 3%. The resulting fabric exhibited a pronounced pliss which withstood numerous launderings.

Example 3 The same procedure was employed as in Example 1 except that the imidazolidone was used at a concentration of 7.5 and the linear copolymer was used in a concentration of 5%. In this example, however, the imidazolidone impregnated fabric was dried with the warp under tension on the tenter frame and the caustic was printed in parallel lines extending lengthwise or warpwise of the fabric. The finished fabric showed a pronounced pliss which was substantially undiminished after numerous washings.

Example 4 The procedure of Example 2 was followed except that the fabric was tensioned both Warpwise and fillingwise during drying after impregnation with the imidazolidone and the caustic paste was printed along two sets of intercepting lines, one of such sets extending at 45 to the filling direction and the other extending at right angles to the first set. A pronounced pliss was produced and it was substantially undiminished after numerous washings.

Example A rayon cellulose acetate having a count of 72 x 60 and a weight of 4.00 yards per pound and comprising spun yarns of a blend of 70% viscose rayon and 30% cellulose acetate in both the warp and in the filling which had been de-sized, brushed and dyed, was impregnated with an aqueous solution of 4% by weight of 1,3-bis- (hydroxymethyl)2-irnidazolidone, 5% of stearyl pyridinium chloride, 1% of pyridine hydrochloride and 36% of an octylphenoxypolyethoxyethanol containing about 35 oxyethylene units per molecule. Excess liquor was removed by squeezing and the fabric was dried on a tenter frame under tension both warpwise and fillingwise, and cured for 20 seconds at 400 F. A caustic paste of the type used in Example 1 was applied in criss-cross lines, one set of which extended at 45 to the length of the fabric and the other at 90 to the first set. A pronounced pliss was obtained which was substantially undiminished on subsequent launderings.

Example 6 The procedure of Example 5 was followed except that the stearyl pyridinium chloride was replaced with 3% of o-ctadecyloxymethyl pyridinium chloride and 2% of a copolymer of 60% ethyl acrylate, 35% methyl acrylate, and 5% of acrylic acid. The pliss fabric retained its pronounced pliss through numerous washings.

The present invention provides pliss fabrics showing a pronounced pucker which is substantially permanent in character. By the present invention, it is possible to produce a higher degree of pucker and a more permanent pucker than by conventional pliss processes. The fabrics are capable of being laundered and scoured under normal conditions without appreciable loss of the puckered effect. By initial stetching and stabilization with the imidazolidone of the entire fabric including theportions to be puckered, the process of the invention is adapted to pliss fabrics that cannot be plissd by conventional methods, such as high count fabrics of tight weave, and fabrics of coarse yarn. Not only are the fabrics resistant to loss of pucker on laundering, but they are highly resistant to loss of pucker on mechanical pressure or under conditions of high humidity. These last two features are extremely important in dress goods Where the wearers frequently exert pressure on the fabric When in a sitting position, often when atmospheric conditions of high humidity prevail.

It is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. A method of producing a pliss fabric comprising impregnating, over its entire area, a fabric of yarns comprising essentially cellulose fibers with an aqueous solution containing 1 to 15% of a cross-linking agent for the cellulose consisting essentially of 1,3-bis(hydroxymethyl)-2-imidazolidone, heating the impregnated fabric with an acidic catalyst at a temperature of at least 200 F. until the fabric is dried and the cellulose reacts with and is cross-linked by the imidazolidone, then impregnating local areas of the fabric with a chemical shrinking agent for cellulose selected from the group consisting of caustic soda. caustic potash, and strong, 'low molecular weight quaternary ammonium bases, then relaxing the impregnated fabric until puckering occurs, then removing the shrinking agent from the fabric with an aqueous washing medium, and drying the fabric.

2. A method of producing a pliss fabric comprising impregnating, over its entire area, a fabric of yarns comprising essentially cellulose fibers with an aqueous solution containing 1 to 15% or" a cross-linking agent for the cellulose consisting essentially of l,3-bis(hydroxy methyl)-2-imidazolidone, heating the impregnated fabric with an acidic catalyst at a temperature of 250 F. to 400 F. while under at least sufiicient tension to remove all slack, said heating being effected until the fabric is dried and the cellulose reacts with and is cross-linked by the imidazolidone, then impregnating by printing local areas of the fabric with an aqueous paste comprising a chemical shrinking agent for cellulose selected from the group consisting of caustic soda, caustic potash and strong, low molecular weight quaternary ammonium bases, then relaxing the impregnated fabric until puckering occurs, then removing the shrinking agent from the fabric with an aqueous washing medium, and drying the fabric.

3. A method of producing a pliss fabric comprising impregnating, over its entire area, a fabric of cotton yarns with an aqueous solution containing 1 to 15% of a crosslinking agent for the cellulose consisting essentially of l,3-bis(hydroxymethyl)-2-imidazolidone, heating the impregnated fabric with an acidic catalyst at a temperature of 250 F. to 400 F. while under at least sufficient tension to remove all slack, said heating being effected for about 20 minutes to 10 seconds respectively until the fabric is dried and the cellulose of the cotton reacts with and is cross-linked by the imidazolidone, then impregnating by printing local areas of the fabric with an aqueous paste comprising a chemical shrinking agent for cellulose selected from the group consisting of caustic soda, caustic potash, and strong, low molecular weight quaternary ammonium bases, then relaxing the impregnated fabric until puckering occurs, then removing the shrinking agent from the fabric with an aqueous washing medium, and drying the fabric.

4. A method of producing a pliss fabric comprising impregnating, over its entire area, a fabric of yarns comprising essentially cellulose fibers with an aqueous solution containing 1 to 15 of a cross-linking agent for the cellulose consisting essentially of l,3-bis(hydroxymethyl)- Z-imidazolidone and l to 7.5% of a textile water-repellent material selected from the group consisting of (1) quaternary ammonium compounds having an aliphatic group of at least eight carbon atoms, (2) Water-insoluble copolymers of 0.5 to 8% by weight of an acid of the class consisting of acrylic acid, methacrylic acid, and itaconic acid with at least one monoethylenically unsaturated copolymerizable ester of these acids, and (3) mixtures of compounds mentioned in (l) and (2), heating the impregnated fabric with an acidic catalyst at a temperature of 250 F. to 400 F. while under at least sufficient tension to remove all slack, said heating being eifected for about 20 minutes to 10 seconds respectively until the fabric is dried and the cellulose reacts with and is cross-linked by the imidazolidone, then impregnating by printing local areas of the fabricwith an aqueous caustic soda chemical shrinking paste, then relaxing the impregnated fabric until puckering occurs, then removing the caustic from the fabric with an aqueous washing medium, and drying the fabric. 7

5. A method of producing a pliss fabric comprising impregnating, over its entire area, a fabric of cotton yarns with an aqueous solution containing 1 to 15% of a crosslinking agent for the cellulose consisting essentially of l,3-bis(hydroxymethyl)-2-imidazolidone and, as a waterrepellent, 1 to 7.5 of a quaternary ammonium compound having an aliphatic group of at least eight carbon atoms, heating the impregnated fabric with 'an acidic catalyst at a temperature of 250 F. to 400 Fpwhile under at least sufficient tension to remove all slack, said heating being effected for about 20 minutes to 10 seconds respectively until the fabric is dried and the cellulose of the cotton reacts with and is cross-linked by the imidaz} olidone, then impregnating by printing local areas of the fabric with an aqueous chemical shrinking caustic soda paste, then relaxing the impregnated fabric until puckering occurs, then removing the caustic from the fabric with an aqueous washing medium, and drying the fabric.

6. A process as defined in claim in which the quaternary ammonium compound comprises stearyl pyridinium chloride.

7. A process as defined in claim 5 in which the quaternary ammonium compound comprises octadecyl oxy' methyl pyridinium chloride.

8. A method of producing a pliss fabric comprising impregnating, over its entire area, a fabric of cotton yarns with an aqueous solution containing 1 to 15% of a crosslinking agent for the cellulose consisting essentially of 1,3- bis(hydroxymethyl)-2-imidazolidone and, as a waterrepellent, 1 to 7.5% of a water-insoluble copolymer of 0.5 to 8% by weight of an acid of the class consisting of acrylic acid, methacrylic acid, and itaconic acid with at least one other monoethylenically unsaturated copolymerizable compound, heating the impregnated fabric with an acidic catalyst at a temperature of 250 F. to 400 F. while under at least sufficient tension to remove all slack, said heating being effected for about 20 minutes to 10 seconds respectively until the fabric is dried and the cellulose of the cotton reacts with and is cross-linked by the imidazolidone, then impregnating by printing local areas of the fabric with an aqueous caustic soda chemical shrinking paste, then relaxing the impregnated fabric until puckering occurs, then removing the caustic from the fabric with an aqueous washing medium, and drying the fabric.

9. A method of producing a pliss fabric comprising impregnating, over its entire area, a fabric of cotton yarns with an aqueous solution containing 1 to of a crosslinking agent for the cellulose consisting essentially of 1,3- bis(hydroxymethyl)-2-imidazo1idone and, as a waterrepellent, 1 to 7.5% of a mixture of (1) a quaternary ammonium compound having an aliphatic group of at least eight carbon atoms and (2) a water-insoluble copolymer of 0.5 to 8% by weight of an acid of the class consisting of acrylic acid, methacrylic acid, and itaconic acid with at least one other monoethylenically unsaturated copolymerizable compound, heating the impregnated fabric with an acidic catalyst at a temperature of 250 F. to 400 F. while under at least sufiicient tension to remove all slack, said heating being effected for about minutes to 10 seconds respectively until the fabric is dried and the cellulose of the cotton reacts with and is cross-linked by the imidazolidone, then impregnating by printing local areas of the fabric with an aqueous caustic soda chemical shrinking paste, then relaxing the impregnated fabric until puckering occurs, then removing the caustic from the fabric with an aqueous washing medium, and drying the fabric.

10. A method of producing a pliss fabric comprising impregnating, over its entire area, a fabric of cotton yarns with an aqueous solution containing 1 to 15% of a crosslinking agent for the cellulose consisting essentially of 1,3- bis(hydroxymethyl) -2-imidazolidone and, as a waterrepellent, 1 to 7.5% of a mixture of (1) a quaternary ammonium compound having an aliphatic group of at least eight carbon atoms and (2) a copolymer of 0.5 to

8% by weight of methacrylic acid with both ethyl acrylate and methyl methacrylate, heating the impregnated fabric with an acidic catalyst at a temperature of 250 F. to 400 F. while under at least sufficient tension to remove all slack, said heating being effected for about 20 minutes to 10 seconds respectively until the fabric is dried and the cellulose of the cotton reacts with and is cross-linked by the imidazolidone, then impregnating by printing local areas of the fabric with an aqueous caustic soda chemical shrinking paste, then relaxing the impregnated fabric until puckering occurs, then removing the caustic from the fabric with an aqueous washing medium, and drying the fabric.

11. As an article of manufacture a pliss fabric stabilized against loss of pucker on laundering produced by the process of claim 1.

12. As an article of manufacture a pliss fabric stabilized against loss of pucker on laundering produced by the process of claim 4.

13. As an article of manufacture a pliss fabric stabilized against loss of pucker on laundering produced by the process of claim 5.

14. As an article of manufacture a pliss fabric stabilized against loss of pucker on laundering produced by the process of claim 6.

15. As an article of manufacture a pliss fabric stabilized against loss of pucker on laundering produced by the process of claim 7.

16. As an article of manufacture a pliss fabric stabilized against loss of pucker on laundering produced by the process of claim 8.

17. As an article of manufacture a pliss fabric stabilized against loss of pucker on laundering produced by the process of claim 9.

18. As an article of manufacture a pliss fabric stabilized against loss of pucker on laundering produced by the process of claim 10.

19. An article as defined in claim 18 in which the quaternary ammonium compound comprises stearyl pyridinium chloride.

20. An article as defined in claim 18 in which the quaternary ammonium compound comprises octadecyl oxymethyl pyridinium chloride.

References Cited in the file of this patent UNITED STATES PATENTS 2,244,767 Corbett June 10, 1941 2,373,136 Hoover et al Apr. 10, 1945 FOREIGN PATENTS 547,846 Great Britain Sept. 15, 1942 1,061,107 France Nov. 25, 1953 OTHER REFERENCES Marsh, John T.: An Introduction to Textile Finishing, Second Impression 1948, page 107.

Shapiro: Rayon and Synthetic Textiles, Sept. 1949, pages 58-60. 

1. A METHOD OF PRODUCING A PLISSE FABRIC COMPRISING IMPREGNATING, OVER ITS ENTIRE AREA, A FABRIC OF YARNS COMPRISING ESSENTIALLY CELLULOSE FIBERS WITH AN AQUEOUS SOLUTION CONTAINING 1 TO 15% OF A CROSS-LINKING AGENT FOR THE CELLULOSE CONSISTING ESSENTIALLY OF 1,3-BIS(HYDROXYMETHYL)-2-IMIDAZOLIDONE, HEATING THE IMPREGNATED FABRIC WITH AN ACIDIC CATALYST AT A TEMPERATURE OF AT LEAST 200*F. UNTIL THE FABRIC IS DRIED AND THE CELLULOSE REACTS WITH AND IS CROSS-LINKED BY THE IMIDAZOLIDONE, THEN IMPREGNATING LOCAL AREA OF THE FABRIC WITH A CHEMICAL SHRINKING AGENT FOR CELLULOSE SELECTED FROM THE GROUP CONSISTING OF CAUSTIC SODA, CAUSTIC POTASH, AND STRONG, LOW MOLECULAR WEIGHT QUATERNARY AMMONIUM BASES, THEN RELAXING THE IMPREGNATED FABRIC UNTIL PUCKERING OCCURS, THEN REMOVING THE SHRINKING AGENT FROM THE FABRIC WITH AN AQUEOUS WASHING MEDIUM, AND DRYING THE FABRIC. 